Corona discharge apparatus

ABSTRACT

Apparatus is disclosed for simultaneously exposing a photosensitive member to image radiation and imparting charge to the photosensitive member. A plurality of needle electrodes is positioned intermediate the photosensitive member and a conductive member. An image radiation generator is positioned adjacent a translucent expanse of the conductive member.

I United States Patent [1 1 n 11 3,744,898 Kurahashi et al. July 10, 1973 CORONA DISCHARGE APPARATUS [56] References Cited [75] Inventors: Akira Kurahashi; Masayoshi UNITED STATES PATENTS Ishihara; Giichi Marushima, all of 3,536,483 10/1970 Watanabe et a1 355/3 X Tokyo, Japan 3,220,324 11/1965 Snelling 250/495 ZC X 3,254,215 5/1966 250/495 ZC 1 Asslgfleei Canon Kabushlkl Kalil, TOkYO, 2,932,742 4/1960 Ebert 250/495 ZC Japan 3,307,034 2/1967 Bean 250/495 ZC [22] Filed: Sept. 23, 1971 PP N95 183,112 Primary Examiner-Robert P. Greiner Related Application m Atmrney- Elmer R. Helferich..lames J. Daley et al. [62] Division of Ser. No. 777,215, Nov. 20, 1968, Pat. No.

57 ABSTRACT 30 Foreign Application Priority Data Apparatus is disclosed for simultaneously exposing a Nov 28 1967 13 an 42 [76631 photosensitive member to image radiation and impart- 1 1967 Japan 4251053 ing charge to the photosensitive member. A plurality of A l 1 Japan 43/121307 needle electrodes is positioned intermediate the photop l p sensitive member and a conductive member. An image [52] U 8 Cl 355/3 250/49 5 ZC radiation generator is positioned adjacent a translucent s1 nie cllixj i I I IIIIIIII G03g 15/00 expanse cmducfive member- [58] Field of Search 355/3, l7; 11 Claims, 16 Drawing Figures 250/495 ZC; 317/262 A Pmmaow 3.744.898

SHE 1 U? 4 I VEN 'I'OR. AKIRA KURASHI,

MASAYOSHI ISHIHARA a m! 8)" 011cm MARUSHIMA Attorneys or Applicants PAIENIED JUL 1 men 3, 7 4, 9

sum 2" or 4 FIGS FIG.6

l N VEN'I JR AKlRA KU RAHAS HI I MASAYOSHI ISHIHARA and GIICHI MARUSHIMA Attorneys for Applicants PATENIEH JUL 1 0 I975 FIG.9

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Attorneys for Applicants Pmemzuw w 3.744.898

SHEEI h 0f 4 INVENTOR. AKIRA KURAHASHI, MASAYOSHI ISHIHARA and BY (311cm MARUSHIMA Attorneys for Applicants 1 CORONA DISCHARGE APPARATUS This is a division of application Ser. No. 777,215, filed on Nov. 20, 1968 and now US. Pat. No. 3,624,392.

This invention relates to improved corona dischargers for electrophotography.

Discharging electrodes for use in corona dischargers for impressing an electrostatic charge on a photosensitive layer may be classified in accordance with the type of electrode which is used, namely, fine metal wires such as tungsten filaments and the like, or needle electrode structures. A typical corona discharger which uses the needle electrode structure is disclosed in US. Pat. application Ser. No. 744,117, filed July 11, 1968 wherein the main discharge occurs between the needle electrode and a shielding member opposite the needle electrode and the photosensitive layer is charged by a peripheral electric field produced around the main discharge. This invention is directed to an improvement of such needle electrode corona discharger.

In the referenced arrangement, the main discharge is directed from each of the needles provided on the electrode structure to the shielding member or wire facing the needles and the generation of an electric field around the main discharge is essentially limited to the vicinity of the needle ends. The charging region is thus necessarily narrow. In order to solve this problem, it is necessary to increase the number of the needles of the electrode structure, apply higher voltage to the electrode structure or take other expedients. Such dischargers are complicated in structure or require a high degree of insulation between the components used therein.

Accordingly, it is an object of the invention to provide an improved highly efficient corona discharger for electrophotography.

It is another object of the invention to widen the charging region established between each electrode and the shielding member and increase the charging efficiency of the referenced corona discharger.

Corona dischargers of high charging efficiency in accordance with the invention are efiectively applied not only to single corona discharging but also to double corona discharging, and in latter case other advantages are provided as described hereinafter.

It is thus another object of the invention to efficiently impress a uniform charge on a photosensitive sheet by providing stable positive and negative corona discharges.

The efficient dischargers herein require a high voltage source of relatively low output potential, and high quality images are obtained without charging irregularities. In a preferred embodiment of the invention, such corona dischargers are applied to electrostatic imageforming processes.

Thus, it is another object of the invention to provide corona dischargers for electrostatic image-forming processes wherein a photosensitive sheet is charged and simultaneously exposed uniformly.

In use of single corona dischargers there arises a difficult problem in that the photosensitive sheet cannot be easily separated from the electrode plate supporting the advancing sheet. Thus, in an automatic continu- It is thus a further object of the invention to prevent a photosensitive sheet from electrostatically adhering to its supporting electrode member to thereby improve feeding of the photosensitive sheet.

An aspect of the invention is to widen the corona discharging patterns radially to avoid concentrating the discharge on restricted points and thereby to expand ionized regions, i.e., charging regions, several times in area.

It is another object of the invention to provide increased electric field intensity to obtain high ion concentration and uniform electrostatic charge even if high voltage is applied between the needle electrode structure and the shielding member.

Other aspects of the invention are to apply lower voltage to a positive electrode of a double corona discharger than that applied to the negative electrode thereof and to provide greater spacing between the adjacent needles of the negative electrode structure than between the positive electrode structure.

It is another object of the invention to cause a photosensitive surface to be charged uniformly and simultaneously to be exposed to light over the full width of the discharger to provide images of good quality without charging irregularities.

It is another aspect of the invention to feed a photosensitive sheet smoothly without substantial mechanical resistance.

The invention will be better understood from the following description taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of the prior art discharger consisting of a needle electrode structure and two shield plates.

FIG. 2 is a schematic diagram of a discharger in accordance with the present invention.

FIG. 3 indicates the state of ionization of ambient medium in the vicinity of a positive electrode during corona discharge.

FIG. 4 indicates the state of ionization of ambient medium in the vicinity of a negative electrode during corona discharge.

FIG. 5 is a plan view a pOsitive sawtooth electrode structure of corona dischargers in accordance with the invention.

FIG. 6 is a plan view of a'negative sawtooth electrode structure of corona dischargers in accordance with the invention.

FIG. 7 is a schematic diagram of a double corona discharger in accordance with the present invention.

FIG. 8 is a schematic diagram of an embodiment of the invention wherein two shielding membersface a center electrode.

FIG. 9 is a cross-sectional view of a corona discharger having the electrode arrangement shown in FIG. 8.

FIG. 10 is a diagram of another embodiment of the invention wherein a transparent electrode plate is provided with a plurality of needle electrodes.

FIG. 11 is a cross-sectional view of a corona discharger having the electrode arrangement shown in ously operating system, it is difficult to feed the photosensitive sheet smoothly.

FIG. 10.

FIGS. 12 and 13 show modified embodiments of electrode structures wherein a plurality of electrodes are disposed on transparent plate members.

FIG. 14 is a cross-sectional view of a corona discharger in accordance with the invention wherein a rotatable electrode is used. e

FIG. is a cross-sectional view of another form of corona discharger wherein two needle electrode structures are opposed to each other.

FIG. 16 shows cross-sectional view of another discharger wherein three discharging wires are utilized.

Referring to FIG. 1, there is shown an arrangement of the above-discussed prior art corona discharger hav- 'ing a needle electrode structure and a pair of shielding plate members. Needle electrode structure 1 is provided with a plurality of needles 2, each comprising an elongated body tapering to a corona discharge point, alternatively projecting from opposite sides of the structure. Shielding plate members 3 are disposed adjacent the electrode structure opposite needles 2. The negative terminal of power supply 4 is connected to needle electrode structure 1 and the positive terminal is connected to shielding plate members 3 to apply voltage therebetween. In the illustrated example, both shielding members 3 are grounded, as shown in FIG. 1, and thepositive terminal of the power supply is also grounded. In such prior art arrangement, upon the application of voltage between the electrode structure and the shielding members, continuous corona discharge F is directed from the end of each needle of the electrode structure to the shielding members. Such corona discharge is concentrated on restricted points on the shielding members. Accordingly, it is evident that ionized regions, and thus charging areas, are limited.

FIG. 2 shows a corona discharger having a pair of facing shielding members and a needle electrode structure in accordance with the present invention. Like elements shown in FIG. 2 have the same reference numerals to those of FIG. 1. Needle electrode structure 1 may take various fonns such as the form wherein a plurality of projections are integrally formed on opposite sides, the form of a sawtooth electrode or the like, and such forms fall within the category of needle electrode structure as described herein. Preferably, electrode structure 1 has alternating projections, called needles", on opposite sides thereof. In FIG. 2, each of shielding members 3' is formed with corrugations insuch a manner that each of the concave portions thereof forms an are centered around the end of each needle of the electrode structure. Thus, the cycle of the corrugations of the shielding members corresponds to the spacing between the adjacent needles or projections.

According to one embodiment of the present invention each needle is spaced from the adjacent needle by 10 mm, the bottom of each concave portion of the shielding members is spaced from the end of the opposing needle by 10 mm, and the distance between the end of each needle and the photosensitive surface of the chargeable medium (not shown) is 10 mm. Negative voltage of 7 KV is applied from power supply 4 to needle electrode structure 1, and shielding members 3 are grounded or connected to the positive terminal of the power supply. Upon the application of voltage between needle electrode structure 1 and shielding members 3', each corona discharge does not concentrate on a point location on the shielding members as above-discussed, but spreads radially, and therefore ionized regions and charging areas are widened. In the FIG. 2 embodiment, the charging regions are extended about several times as compared with the prior art discharger of FIG. l.

The corona discharger shown in FIG. 2 is applicable effectively not only to single corona dischargers but also to double corona dischargers. Before discussing the illustrated embodiments thereof, double corona dischargers will be discussed. In double corona dischargers both positive and negative corona discharges are simultaneously carried out. Where needle electrode structures are used as electrodes of the corona discharger, development of the negative corona discharge is relatively difficult as compared with that of the positive corona discharge. This phenomenon is, in general, called polarity effect. In the case of the positive corona discharge, electrons between electrodes are attracted by the positive electrode and then collide in transit with neutral particles, thereby ionizing the neutral particles. Then, light electrons quickly reach the positive electrode to discharge, while heavier positive ions remain unmoved substantially. The positive ions are distributed in a dendriforrn as space charges, as shown in FIG. 3. In effect, these space charges provide an extension of the positive electrode.

On the other hand, in the case of negative discharge, secondary electrons produced by electron bombardment of neutral particles cannot enable ionization due to the electric field of the negative electrode, and the secondary electrons are repelled thereby to the negative electrode. Thus, the distribution of the secondary electrons becomes radial, with the result that negative corona discharge cannot be readily established. Under such conditions, when voltages of the same magnitudes are applied to the positive and negative needle electrode structures of a double corona discharger, positive corona discharge'is unstable and tends toward spark discharge due to the polarity effect described hereinbefore, while negative corona discharge is not easily established, and therefore it is impossible to impress a suitable charge on a photosensitive sheet.

In accordance with one embodiment of the present invention, a needle electrode corona discharger is operated by applying lower voltage to the positive electrode structure than that applied to the negative electrode structure.

According to another embodiment of the invention,

as shown in FIG. 5, positive electrode structure 1 is made of stainless steel or other conductive material of about one-tenth mm in thickness, and a plurality of sawtooth electrodes 2 are formed altematingly on opposite sides thereof. The end of each electrode is of wedge form. Negative electrode structure 1' for use with the positive electrode structure shown in FIG. 5 is illustrated in FIG. 6 and is structurally similar thereto with the exception that spacing P between the peaks of adjacent sawtooth electrodes 2' of the negative structure is greater than spacing P between the peaks of the adjacent sawtooth electrodes of the positive structure shown in FIG. 5. The needle ends on each side of these positive and negative electrode structures are arranged opposite a shielding member, and the positive and negative electrode structures are arranged on the opposite sides of a photosensitive sheet. If desired, the needle ends of each of the electrode structures may be bent at a desired angle.

According to a further embodiment of the invention,

the two embodiments discussed above are preferably combined. In other words, voltages of different magnitudes are applied to differently formed electrode structures. More specifically, lower voltage is applied to a positive electrode structure having narrow electrode spacing, while higher voltage is applied to a negative electrode structure having wide electrode spacing. In such double corona discharging schemes, the development of corona discharge is suppressed and stabilized so as not to tend toward spark discharge at the side of positive electrode structure, and the development of corona discharge is facilitated at the side of the negative electrode structure. Therefore, double corona dischargers in accordance with the invention maintain stable and continuous corona discharging conditions during operation and are capable of impressing satisfactory charge on a photosensitive sheet without charge irregularities. In addition, according to the present invention, charging efficiencies are considerably improved.

In the FIG. 7 schematic diagram of a double corona discharger in accordance with the present invention, negative electrode structure 1' is arranged at one side of photosensitive sheet P, while positive electrode structure 1 is disposed opposite the negative electrode structure on the other side of photosensitive sheet P. A pair of shielding members 3' and 3' face each other aside negative electrode structure 1'. Similarly, a pair of shielding members 3 and 3 face each other aside positive electrode structure 1. These shielding members are preferably corrugated, for example, in such manner as described hereinbefore in connection with FIG. 2. Negative electrode structure 1' is connected to the negative terminal of power supply 4, and shielding members 3' and 3 are connected to the positive terminal of the power supply. On the other hand, positive electrode structure I is connected to the positive terminals of power supply 4, and shielding members 3 and 3 are connected to the negative terminal of power supply 4. In accordance with one embodiment of the present invention, negative and positive electrode structures 1 and l are different in width, and therefore the sides of the negative and positive electrode structures are not aligned with each other.

In conventional double corona dischargers, one electrode structure is arranged in alignment with the other electrode structure, and corona discharges established on opposite sides of the photosensitive sheet located between the respective electrode structures are necessarily in alignment with one another at the ends of the negative and positive electrode structures. In such corona discharger, since high voltage is required (for example 10 KV) to establish charging regions sufficient to apply a satisfactory charge to the sheet, a high electric field is set up between negative and positive electrode structures 1' and 1. As a result, such positive ion streams as plasma are produced which are inherent in negative corona discharge, and non-charging regions are partially caused. In addition, there is a possibility that the positive ion streams grow and that the corona discharge tends toward spark discharge.

With the arrangement constructed in accordance with the invention and shown in FIG. 7, since the negative and positive electrode structures are not aligned with each other at the ends thereof but are displaced at predetermined distance X, peripheral electric fields F' and f are displaced from each other correspondingly to the displacement of the electrode structures, with the result that ionized or charged regions are extended. Further, since the distance between the electrode structures is sufficiently large, high voltage may be applied to produce high strength electric fields. Thus, ionized regions are extended and ion concentration is increased. Accordingly, uniform charging of the photosensitive surface of the sheet is attainable over extended charge regions.

In a typical embodiment, the same structure as in the aforementioned embodiment was provided in respect of the spacing between adjacent needle electrodes, the distance between the needle end of the electrode structure and the shielding member, and the distance between the needle ends and the photosensitive surface. Displacement X between the side of one electrode structure and the corresponding side of the other structure was 4 mm, the applied voltage was 4.2 KV at the negative electrode structure as well as the positive one, and the photosensitive sheet was fed at the rate of 4 cm. per second. With this arrangement, the photosensitive surface of the sheet was given a uniform and satisfactory charge.

Photosensitive sheets chargeable by the present invention may take various forms. It is especially preferable to apply the corona discharger of the present invention to the photosensitive member disclosed in the US. Pat. application Ser. Nos. 563,899 and 571,538, filed July 8, 1966 and Aug. 10, 1966 respectively, i.e., a sandwich-like photosensitive member having a photoconductive layer interposed between a conductive base and an insulating layer. After applying a primary charge to such photosensitive member, an electrostatic image pattern is formed on the insulating layer of the photosensitive member by irradiating a light pattern thereon and simultaneouslyapplying alternating current corona discharge thereto. Alternatively, the electrostatic image pattern can be formed by direct current secondary discharge of polarity reverse to that of the primary discharge, instead of the alternating corona discharge mentioned above. It should be noted that a photosensitive sheet which has a photoconductive layer interposed between two insulating layers may also be conveniently charged by the invention.

In general, a corona discharger in accordance with theinvention has a discharging electrode disposed at the center of its housing and discharge is provided between this discharging electrode and shielding members arranged opposite the electrode. On the other hand, a simultaneous exposing discharger is arranged to radiate the intended pattern onto a photosensitive layer through the discharger housing. Where a discharger with needle electrode structure is applied in such simultaneous exposing process, exposure irregularities would be caused and the quality of image pattern produced on the photosenstive medium would be derogated considerably, because exposure would be disturbed by the discharging electrodes located within the light path for exposure.

In the FIG. 8 embodiment of the invention, the needle electrode corona discharger is effectively applied to the simultaneous exposing process without occurrence of the above-discussed problem. As shown in FIG. 8, counter-electrode 16 made of a conductive wire or a fine plate is disposed centrally between two facing needle electrode structures 17 and 17,. FIG. 9 shows a corona discharger which utilizes the electrode arrangement shown in FIG. 8. Needle electrode structures 17 and 17, are connected to the negative terminal of power supply 18, and counter-electrode 16 is connected to the grounded positive terminal of the power supply. When high voltage is applied between the needle electrode structures and the counter-electrode, corona discharges occur between electrode structure 17 and counter-electrode l6 and between electrode structure 17 and counter-electrode 16. In this manner, the photosensitive surface of photosensitive sheet 15 is charged and simultaneously the exposure is made from lamp 14 through the light path formed between needle electrode structures 17 and 17 inclusive of transparent member 13. In this case, counter-electrode 16 is very fine to the extent that it is negligible (for example, 1 mm), and therefore the charging width 1 is substantially equal to the exposure width. Thus, in accordance with the coronadischarger with needle electrode structures of the invention, the exposing and charging steps are simultaneously and effectively performed without irregularities.

In the illustrated embodiment, the needle electrode structure was made of stainless steel or other conductive material of the order of 0.1 mm in thickness and a plurality of sawteeth were formed at the one side. Preferably, the positive electrode structure has sawteeth at intervals of 4 mm, and the negative electrode structure has sawteeth at intervals of 8 mm. A pair of the needle electrode structures were prepared in the above manner and were arranged so that the sawteeth of one electrode structure alternated with those of the other electrode structure with space I, being 8 mm and space 1 being 10 mm. A voltage of 8 KV was applied between the needle electrode structures and the counter-electrode to effectively operate the corona discharger in accordance with the invention. To obtain the same effect, the sawtooth electrode structure may be replaced by an electrode structure wherein an elongated conductor is provided with a plurality of needles projecting therefrom at predetermined intervals.

FIGS. 10 and 11 show another arrangement of needle form electrodes and corona discharger utilizing the same. Transparent electrode plate 19 made of NESA glass or the like is provided with a plurality of needlelike electrodes 10 attached to its oppositesides by transparent conductive adhesive. Alternatively, transparent needle electrodes may be formed on the transparent plate by vaporization. Then, a pair of shielding members 12 are arranged opposite needle electrodes 10 of the electrode structure. As shown in FIG. 11, the negative terminal of power supply 18 is connected to transparent conductive coating 11 on plate 19, and the grounded positive terminal of the power supply is connected to shielding members 12. When voltage is applied between electrode structure 19 and shielding members 12, corona discharge is initiated therebetween. Exposure is simultaneously performed through transparent electrode structure 19 by light radiated from light source 14. In this embodiment, the exposure width is equal to twice discharging width I plus electrode width 1 and the exposure width may be easily determined on the basis of the electrode width 1 The electrode structure as shown in FIG. 10 may be formed by depositing metal vaporized film 11 on glass plate 19 in such a manner that sawteeth 10 are formed on the opposite sides of the vaporized film, as shown in FIG. 12. Alternatively, the needle electrode structure in accordance with the invention may be fonned by fixing conductive material such as tungsten wire or stainless wire 10" to the metal-depositied film by conductive adhesives, as shown in FIG. 13.

In accordance with the corona dischargers of the in-' vention, uniform and satisfactory charge can be impressed on a photosensitive sheet moving at a speed of 5 7 cm. per second, and simultaneous exposure can be effectively carried out through the full width of the electrode structure without irregularities. Accordingly, image patterns of good quality can be obtained, and simultaneous exposing and charging process can be improved.

In another embodiment of the invention, the corona discharger is characterized by use of a rotatable roller electrode as the counter-electrode provided on one side of the advancing photosensitive sheet. In prior art devices, as the photosensitive sheet is charged by the corona discharger during operation, it adheres electrostatically to a stationary electrode plate, and therefore in many cases it is difficult to smoothly feed the photosensitive sheet.

The problem can be solved by providing a rotatable roller electrode facing the discharging electrode. FIG. 14 shows a corona discharger and its associated elements so constructured in accordance with the invention. Housing 21 of the discharger includes needle electrode structure 22 and facing shielding plate member 23. Rotatable roller electrode 24 is provided adjacent the discharge opening of housing 21 for receiving an advancing photosensitive sheet P guided by guiding plate 30. Roller electrode 24 may be freely rotatable or may be driven by a driving mechanism (not shown).

FIG. 15 shows another corona discharger embodiment of the invention wherein shielding plate 23 and facing needle electrode structures 22' are accommodated in housing 21. Rotatable electrode 24 is positioned opposite shielding plate member 231'. Needle electrode structures'22' are connected to a negative potential source, and shielding plate member 23 and rotatable roller electrode 24 are connected to a grounded positive potential.

FIG. 16 shows another embodiment of the present invention in which a housing has three fine metal wires 25 and shielding member 23" accommodated therein and rotatable electrode 24 is provided in front of the opening of the housing.

Where a rotatable electrode is used as the feeding mechanism for advancing photosensitive sheets, the problem of adhesion of the sheets to the electrode is effectively solved. In practice, when a roller electrode of 16 mm diameter was used, the photosensitive sheet was advanced at the rate of 50 mm per second and a negative voltage of 7 KV was applied to the electrode structure, successful results were provided. Whereas in the prior art devices, the photosensitive sheet has encountered considerable feed resistance, with the use of a rotatable electrode, the photosensitive paper is smoothly advanced without appreciable resistance.

It should be noted that one or more of the embodiments described herein can be advantageously combined with another or other embodiments.

What is claimed is 1. Apparatus for simultaneously image-exposing and imparting corona discharge to a photosensitive member in transit therethrough, comprising:

a. a conductive sidewall having one. end juxtaposed with said photosensitive member in said transit thereof and an opposite end;

b. means disposed adjacent said sidewall opposite end for defining an optical opening;

c. electrodes disposed below said optical opening defining means, each electrode comprising an elongated body tapering to a corona discharge point, each elongated body being fixedly disposed in substantial non-perpendicular relation to said photosensitive member in said transit thereof for directing corona discharge onto both said conductive sidewall and said photosensitive member in said transit thereof; and

d. image-generating means supported above said optical opening defining means for applying a radiant energy image through said optical opening onto said photosensitive member in said transit thereof.

2. The apparatus claimed in claim 1 further including a voltage supply and means interconnecting said voltage supply and said electrodes.

3. The apparatus claimed in claim 2 including first and second pluralities of said electrodes and another conductive sidewall having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end disposed adjacent said means defining an optical opening, said first electrode plurality directing corona discharge onto one said sidewall and said second electrode plurality directing corona discharge onto the other said sidewall and further including means interconnecting said voltage supply and said sidewalls.

4. The apparatus claimed in claim 3 wherein said first electrode plurality is staggered with respect to said second electrode plurality.

5. Apparatus for simultaneously image-exposing and imparting corona discharge to a photosensitive member in transit therethrough, comprising:

a. a conductive sidewall having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end;

b. means disposed adjacent said sidewall opposite end for defining an optical opening;

c. a plurality of electrodes, each electrode comprising an elongated body tapering to a corona discharge point for applying corona discharge to said photosensitive member in said transit thereof;

(1. a voltage supply;

e. means interconnecting said voltage supply and said electrodes including a translucent conductive element supporting said electrodes, disposed below said optical opening and substantially coextensive 10 with said optical opening; and

f. image-generating means supported above said optical opening and applying a radiant energy image through said optical opening onto said photosensitive member in said transit thereof.

6. The apparatus claimed in claim 5 wherein said electrodes are adhesively secured to said translucent conductive element.

7. The apparatus claimed in claim 4 wherein said electrodes are adhesively secured to the periphery of said transparent conductive element.

8. The apparatus claimed in claim 6 wherein said electrodes each comprise a thin conductive strip coextensive with said optical opening.

9. The apparatus claimed in claim 5 wherein said electrodes each comprise a metal deposited on said translucent conductive element.

10. Apparatus for simultaneously image-exposing and imparting corona discharge to a photosensitive member in transit therethrough, comprising:

a. a conductive member having first and second sidewalls, each having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end;

b. means disposed adjacent said sidewall opposite ends for defining an optical opening;

c. first and second pluralities of electrodes disposed below said optical opening and intermediate said sidewalls, each electrode comprising an elongated body tapering to a corona discharge point;

d. a voltage supply;

e. a conductive element disposed intermediate said first and second electrode pluralities, each of said electrode pluralities directing corona discharge onto both said conductive element and said photosensitive member in said transit thereof;

f. means interconnecting said voltage supply, said first and second electrode pluralities and said conductive element; and

g. image-generating means supported above said optical opening for applying a radiant energy image through said optical opening onto said photosensitive member in said transit thereof.

11. The apparatus claimed in claim 10 wherein said first electrode plurality is staggered with respect to said second electrode plurality.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3,744,898 v Dated Julv 10. 1973 Invent0r(s) Akira Kurahashi et al.

It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Title page, item [30] insert Deco 28, Japan-000000o0oooq42/1l0564""0 Column 2, line 45, after "view" insert --of--,

Column 2, line 45, "pOsitive" should read --positive--.

Column 10, line-9 (claim 7), "4" should read --6--.

Signed and Sealed this Nineteenth D3) 0f April 1977 [SEAL] Attesl:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofPaIents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N 3,744,898 Dated J11]; 10. 1973 Ihv n fl Akira Kurahashi et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title page, item [30] insert "DQC. 28, 0 o o o o I o o o a Column 2, line 45, after "View" insert --of-- Column 2, line 45, "pOsitive" .should read "positive".

Colunm 10, line- 9 elem 7), "4" should read 6--.

V Signed and Sealed this Nineteenth Day of April 1977 [SEAL] Arrest:

' RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner uflarents and Trademarks 

1. Apparatus for simultaneously image-exposing and imparting corona discharge to a photosensitive member in transit therethrough, comprising: a. a conductive sidewall having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end; b. means disposed adjacent said sidewall opposite end for defining an optical opening; c. electrodes disposed below said optical opening defining means, each electrode comprising an elongated body tapering to a corona discharge point, each elongated body being fixedly disposed in substantial non-perpendicular relation to said photosensitive member in said transit thereof for directing corona discharge onto both said conductive sidewall and said photosensitive member in said transit thereof; and d. image-generating means supported above said optical opening defining means for applying a radiant energy image through said optical opening onto said photosensitive member in said transit thereof.
 2. The apparatus claimed in claim 1 further including a voltage supply and means interconnecting said voltage supply and said electrodes.
 3. The apparatus claimed in claim 2 including first and second pluralities of said electrodes and another conductive sidewall having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end disposed adjacent said means defining an optical opening, said first electrode plurality directing corona discharge onto one said sidewall and said second electrode plurality directing corona discharge onto the other said sidewall and further including means interconnecting said voltage supply and said sidewalls.
 4. The apparatus claimed in claim 3 wherein said first electrode plurality is staggered with respect to said second electrode plurality.
 5. Apparatus for simultaneously image-exposing and imparting corona discharge to a photosensitive member in transit therethrough, comprising: a. a conductive sidewall having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end; b. means disposed adjacent said sidewall opposite end for defining an optical opening; c. a plurality of electrodes, each electrode comprising an elongated body tapering to a corona discharge point for applying corona discharge to said photosensitive member in said transit thereof; d. a voltage supply; e. means interconnecting said voltage supply and said electrodes including a translucent conductive element supporting said electrodes, disposed below said optical opening and substantially coextensive with said optical opening; and f. image-generating means supported above said optical opening and applying a radiant energy image through said optical opening onto said photosensitive member in said transit thereof.
 6. The apparatus claimed in claim 5 wherein said electrodes are adhesively secured to said translucent conductive element.
 7. The apparatus claimed in claim 4 wherein said electrodes are adhesively secured to the periphery of said transparent conductive element.
 8. The apparatus claimed in claim 6 wherein said electrodes each comprise a thin conductive strip coextensive with said optical opening.
 9. The apparatus claimed in claim 5 wherein said electrodes each comprise a metal deposited on said translucent conductive element.
 10. Apparatus for simultaneously image-exposing and imparting corona discharge to a photosensitive member in transit therethrough, comprising: a. a conductive member having first and second sidewalls, each having one end juxtaposed with said photosensitive member in said transit thereof and an opposite end; b. means disposed adjacent said sIdewall opposite ends for defining an optical opening; c. first and second pluralities of electrodes disposed below said optical opening and intermediate said sidewalls, each electrode comprising an elongated body tapering to a corona discharge point; d. a voltage supply; e. a conductive element disposed intermediate said first and second electrode pluralities, each of said electrode pluralities directing corona discharge onto both said conductive element and said photosensitive member in said transit thereof; f. means interconnecting said voltage supply, said first and second electrode pluralities and said conductive element; and g. image-generating means supported above said optical opening for applying a radiant energy image through said optical opening onto said photosensitive member in said transit thereof.
 11. The apparatus claimed in claim 10 wherein said first electrode plurality is staggered with respect to said second electrode plurality. 